Tiacumicins are a family of structurally related compounds that contain the 18-membered macrolide ring shown below.

At present, several distinct Tiacumicins have been identified and six of these (Tiacumicin A-F) are defined by their particular pattern of substituents R1, R2, and R3 (U.S. Pat. No. 4,918,174; J. Antibiotics, 1987, 575-588).
The Lipiarmycins are a family of natural products closely related to the Tiacumicins. Two members of the Lipiarmycin family (A3 and B3) are identical to Tiacumicins B and C respectively (J. Antibiotics, 1988, 308-315; J. Chem. Soc. Perkin Trans I, 1987, 1353-1359).
The Tiacumicins and the Lipiarmycins have been characterized by numerous physical methods. The reported chemical structures of these compounds are based on spectroscopy (UV-vis, IR and 1H and 13C NMR), mass spectrometry and elemental analysis (See for example: J. Antibiotics, 1987, 575-588; J. Antibiotics, 1983, 1312-1322).
Tiacumicins are produced by bacteria, including Dactylosporangium aurantiacum subspecies hamdenensis, which may be obtained from the ARS Patent Collection of the Northern Regional Research Center, United States Department of Agriculture, 1815 North University Street, Peoria, Ill. 61604, accession number NRRL 18085. The characteristics of strain AB 718C-41 are given in J. Antibiotics, 1987, 567-574 and U.S. Pat. No. 4,918,174.
Lipiarmycins are produced by bacteria including Actinoplanes deccanensis (U.S. Pat. No. 3,978,211). Taxonomical studies of type strain A/10655, which has been deposited in the ATCC under the number 21983, are discussed in J. Antibiotics, 1975, 247-25.
Tiacumicins, specifically Tiacumicin B, show activity against a variety of bacterial pathogens and in particular against Clostridium difficile, a Gram-positive bacterium (Antimicrob. Agents Chemother. 1991, 1108-1111). Clostridium difficile is an anaerobic spore-forming bacterium that causes an infection of the bowel. Diarrhea is the most common symptom but abdominal pain and fever may also occur. Clostridium difficile is a major causative agent of colitis (inflammation of the colon) and diarrhea that may occur following antibiotic intake. This bacterium is primarily acquired in hospitals and chronic care facilities. Because Tiacumicin B shows promising activity against C. difficile, it is expected to be useful in the treatment of bacterial infections, especially those of the gastrointestinal tract, in mammals. Examples of such treatments include but are not limited to treatment of colitis and treatment of irritable bowel syndrome. Tiacumicins may also find use for the treatment of gastrointestinal cancers.
Fermentation processes are used to obtain antibiotics, including Tiacumicins. Antibiotics may be produced by culturing a microorganism in a medium containing readily assimilated sources of carbon, nitrogen, and inorganic salts under submerged aerobic fermentation conditions, until a substantial amount of antibiotic activity is produced as deduced from in-process analyses. Because of rising worldwide demand for antibiotics, there is an ongoing need for improved methods to produce antibiotics.